This invention generally relates to a pump and valve assembly for inflating a prosthesis. More particularly, the invention relates to pressure based mechanisms that inhibit spontaneous inflation of the prosthesis, including stiffening and support mechanisms that also improve the function of the valve.
One common treatment for male erectile dysfunction is the implantation of a penile prosthesis. Such a prosthesis typically includes a pair of inflatable cylinders which are fluidly connected to a fluid (typically liquid) reservoir via a pump and valve assembly. The two cylinders are normally implanted into the corpus cavernosae of the patient and the reservoir is typically implanted in the patient""s abdomen. The pump assembly is implanted in the scrotum. During use, the patient actuates the pump and fluid is transferred from the reservoir through the pump and into the cylinders. This results in the inflation of the cylinders and thereby produces the desired penis rigidity for a normal erection. Then, when the patient desires to deflate the cylinders, a valve assembly within the pump is actuated in a manner such that the fluid in the cylinders is released back into the reservoir. This deflation then returns the penis to a flaccid state.
With inflatable penile prostheses of current designs, spontaneous inflation of the cylinders is known to occasionally occur due to inadvertent compression of the reservoir, resulting in the undesired introduction of fluid into the cylinders. Such inadvertent inflation can be uncomfortable and embarrassing for the patient. This undesirable condition is further described below with reference to a particular prosthetic design.
With reference to FIG. 1, a known pump and valve assembly 8 for use in a penile prosthesis includes a fluid input 10 that is coupled at one end to a reservoir (not shown) and to a housing 12 at its opposite end. Also connected to the housing 12 is a fluid output 14 which, in turn, is connected at its other end to a pair of cylinders (not shown). Linking the fluid input 10 and the fluid output 14 to each other is a common passageway 33, which itself contains a valve assembly that is described in greater detail below. Common passageway 33 is also in fluid communication with a pump bulb 18 that is used to move fluid from the reservoir (not shown) to the cylinders (not shown) in order to inflate the cylinders. The valve assembly located within common passageway 33 includes a reservoir poppet 20 which is biased against a valve seat 24 by a spring 28 and a cylinder poppet 22 which is biased against a valve seat 26 by a spring 30. The springs 28 and 30 are sized so as to keep the reservoir poppet 20 and the cylinder poppet 22 biased against each respective valve seat 24 and 26 under the loads that are encountered when the reservoir is pressurized to typical abdominal pressures.
When the patient wishes to inflate the cylinders, pump bulb 18 is squeezed so as to force fluid from the pump bulb 18 into the common passageway 33. The resulting fluid flow serves to reinforce the force from the spring 28 urging the reservoir poppet 20 against valve seat 24 while at the same time causing compression of the spring 30, and thereby opening cylinder poppet 22. As a result, the fluid travels out through fluid output 14 and into the respective cylinders.
When the patient releases the pump bulb 18 a vacuum is created, thus pulling the poppet 22 back against valve seat 26 (aided by spring 30) and simultaneously pulling the reservoir poppet 20 away from its valve seat 24, against the spring 28. As a result, fluid from the reservoir is thus allowed to flow through the fluid input 10 and into the common passageway 33 passing around the reservoir poppet 20 and into the vacuous pump bulb 18. Once the pump bulb 18 has been filled, the negative pressure is eliminated and the reservoir poppet 20 returns to its normal position. This pumping action of the pump bulb 18 and valve assembly is repeated until the cylinders are fully inflated.
To deflate the cylinders, the patient grips the housing 12 and compresses it along the axis of reservoir poppet 20 and cylinder poppet 22 in a manner such that the wall 13 of the housing 12 contacts the protruding end 21 of the reservoir poppet 20 and forces the reservoir poppet 20 away from valve seat 24. This movement, in turn, causes the reservoir poppet 20 to contact cylinder poppet 22 and force cylinder poppet 22 away from valve seat 26. As a result, both poppets 20 and 22 are moved away from their valve seats 24 and 26 and fluid moves out of the cylinders, through the fluid output 14, through common passageway 33, through the fluid input 10 and back into the reservoir.
Although the springs 28 and 30 are sized to provide sufficient tension to keep poppets 20 and 22 firmly abutted against valve seats 24 and 26 under normal reservoir pressures, it is possible that pressure that exceeds the force provided by the springs could be exerted upon the reservoir during heightened physical activity or movement by the patient. Such excessive pressure on the reservoir may overcome the resistance of the spring-biased poppets 20 and 22 and thereby cause a spontaneous inflation of the cylinders. After implantation, encapsulation or calcification of the reservoir may occur. Encapsulation or calcification of the reservoir can lead to additional problems. In particular, the encapsulation could lead to a more snugly enclosed reservoir, thus increasing the likelihood of spontaneous inflation.
In previous attempts to reduce or eliminate the occurrence of spontaneous inflation, different types of spontaneous inflation preventing valves have been introduced into the pump and valve assembly. Such previous valves are intended to permit the positive flow of fluid to the cylinders only in those circumstances when the patient has forcibly manipulated the valve.
Although such previous valve designs reduce the frequency of spontaneous inflation, several drawbacks do exist. For example, such valves are typically complex, requiring two-handed operation which is a serious drawback to elderly or severely ill patients. Some spontaneous inflation preventing valves also require the application of excessive force in order to manipulate the valves; which may be too demanding for some patients. Furthermore, such valve designs may cause patient discomfort due to the valve size or shape, because of increase in the overall volume of the implant within the patient. This increased size can also lead to interference with the patient""s normal bodily functions. Such previous valve designs typically add undesirable cost to the device as well as increase the complexity of the surgical implantation procedure.
A solution to the above-identified drawbacks is disclosed in co-pending U.S. patent application Ser. No. 09/749,292 entitled xe2x80x9cPRESSURE BASED SPONTANEOUS INFLATION INHIBITORxe2x80x9d which is assigned to the Assignee of the present invention and is incorporated herein by reference. However, the operational efficiency of the prosthesis pump could be further improved by optimizing the operative manipulation of the assembly.
Presently, the pump and valve assemblies used in implantable prostheses share certain characteristics. A compressible pump bulb is attached to the housing and is in fluid communication with the various fluid pathways. In order to inflate the cylinders, the compressible pump bulb is actuated by the patient, thereby urging fluid past the poppets into the cylinders. In order to deflate the cylinders, the valve housing is grasped and squeezed (through the patient""s tissue), causing the poppets to unseat and allow fluid to flow back to the reservoir.
Since the pump and valve assembly is positioned within the patient""s scrotum, the various components of the assembly must be small. As a result, manipulation of the pump and valve assembly is sometimes difficult. For example, patients requiring the use of a penile prosthesis are oftentimes elderly and have a reduced dexterity as a result of aging. Thus, in some instances, even locating the device within the tissue can be a challenge, let alone identifying the correct portion of the assembly to actuate. More specifically, with some patients it may be difficult to determine whether the housing portion of the assembly that leads to release or deflation of the cylinders is being grasped, or whether the bulb portion which would be used to inflate the cylinders is being grasped.
Notably, the length of the valve assembly is determined (at least in one direction) by the size of the various poppets and the distance such poppets must move in order to open and close the various fluid passageways. As a result, such a pump and valve assembly typically is longer in a direction parallel with the poppets. Moreover, in order to release the poppets in an assembly configured in this manner, the patient must grasp the narrower, shorter sidewalls of the assembly and compresses them together. Such a configuration can present challenges insofar as the spring tension of the poppets at the time of desired deflation is typically at a maximum while the surface area of the assembly which must be compressed in order to cause such deflation is at a minimum. This condition can lead to a situation where the patient has difficulty actually compressing the assembly, or in extreme circumstances, actually loses grip of the assembly during such attempts at deflation.
There exists a need for an improved prosthetic penile implant having a spontaneous inflation prevention mechanism that affords convenient operative manipulation by a patient.
The present invention includes a penile pump having a dual poppet arrangement wherein the poppets act as check valves or flow valves. Each poppet is spring-biased against a valve seat, and under normal circumstances, only allows positive fluid flow when a pump bulb is operated, thus causing an increase in fluid pressure which is transferred to the inflatable cylinders. To prevent spontaneous inflation when an overpressurization occurs in the reservoir, the same reservoir pressure is utilized to seal the fluid output against itself or to seal one or both of the poppets against the valve seat. Thus, the fluid is prevented from reaching the cylinders and creating a spontaneous inflation. When the movement or activity generating the overpressure in the reservoir is released, the system should return to equilibrium. Even if overpressurization of the reservoir is occurring, the pressure generated by compressing the pump bulb will far exceed the level of overpressure. Thus, the poppets will open in the normal way, allowing fluid to flow to the cylinders. The use of the overpressure in the reservoir itself to prevent fluid flow to the cylinders can occur in a variety of formats.
In still another embodiment, the reservoir poppet is actually coupled to an outer wall defining a portion of the fluid input. When an overpressurization in the reservoir occurs, this outer wall is forced to expand which simultaneously causes the reservoir poppet to be pulled firmly against the valve seat. This effectively prevents fluid flow from reaching the cylinders and causing a spontaneous inflation.
In yet another embodiment of the present invention, the valve seat is provided with a flexible valve which cooperates with the first poppet to prevent spontaneous inflation which could be caused by excessive pressure in the reservoir. Specifically, pressure in the reservoir and associated valve input is presented to the flexible valve and thus causing the valve to be further forced against the poppet, thus sealing off the input. When inflation is desired however, the negative pressure pulling the first poppet away from the valve seat will allow the desired fluid flow.
In yet still another embodiment, a tapered poppet is utilized in conjunction with a tapered valve seat. Each of these tapers do not exactly match each other, thus providing variable reactions to pressure signals.
In a further embodiment, a section of the reservoir poppet protrudes into the reservoir chamber. This protruding section of the reservoir poppet is coupled to the outer wall of the reservoir chamber. The poppet is coupled to the wall with a connecting spring that permits relative movement between the poppet and the outer wall. The tension of the spring is selected so that it approximates the forces generated by pressurized fluid acting on the wall of the reservoir chamber. However, the spring force is not so great as to prevent the vacuum generated by the pump bulb from opening the poppet. Thus, when the pump bulb is compressed and released, the vacuum forces generated are sufficient to unseat to the reservoir poppet despite its connection to the outer reservoir chamber wall.
In yet still a further embodiment, a relatively large and powerful biasing spring is coupled with the reservoir poppet to exert a relatively large force against the reservoir poppet forcing it into a sealing or closed position. Due to the strong biasing forces of the spring, overpressurization forces generated in the reservoir chamber are insufficient to unseat the reservoir poppet. Simply using such a spring will make it difficult for the vacuum forces generated by compression of the pump bulb to unseat the reservoir poppet. To eliminate this problem, the face of the reservoir poppet, which forms a fluid-tight seal when the reservoir poppet is in a closed position, is made relatively large. That is, the diameter of the face approaches the diameter of the chamber containing the reservoir poppet. Thus, the vacuum forces generated will act over a larger surface area thereby exerting a larger degree of force, which permits the unseating of the reservoir poppet despite the opposing force of the biasing spring.
Because it is difficult to fabricate a housing having a planar wall that interacts with the planar poppet face to form a sufficiently fluid-tight seal, the portion of the housing holding the reservoir poppet contains a pair of spaced lip seals. The position of the lip seal serves two distinct purposes. The first is to prevent fluid pressure generated during over pressurization of the reservoir from engaging a large portion of the poppet face, which would in effect defeat the added strength provided by the biasing spring. The outer seal is also provided so that when a vacuum force is generated, the vacuum cannot act on the front surface of the poppet face which would, in effect, hold the reservoir poppet in a closed position.
In another embodiment of the present invention, the reservoir poppet is configured with a throughbore at a rear portion of the reservoir poppet that is in fluid communication with a passageway and an outlet adjacent to the cylinder poppet. A sliding valve seal is positioned over this section of the reservoir poppet. The sliding valve seal is held against the back wall of the chamber by a spring positioned between the front face of the sliding valve seal and the back face of the suction poppet valve seal. The arrangement of the valve sleeve on the rear of the reservoir poppet is such that fluid is only able to flow through the throughbore and out of the outlet when the valve sleeve is positioned near the rear of the chamber and the front face of the reservoir poppet is firmly seated. In a reservoir overpressurization situation, the valve sleeve is again pressed against the rear of the chamber. However, the reservoir poppet is also forced backwards into the chamber, forcing the throughbore to be occluded by the valve sleeve. This prevents fluid from flowing towards the cylinder poppet which could ultimately lead to spontaneous inflation.
In yet another embodiment, the portion of the housing between the cylinder poppet and the reservoir chamber has been modified. In addition, the reservoir poppet is provided with a unique configuration to interact with the housing structure. The reservoir poppet has a face, similar to the other embodiments, that is spring biased towards a matching valve seat. An annular ring is molded into the housing just behind (towards the cylinder poppet) the valve seat and is sized to interact with the face.
The pump assembly of this embodiment has two states, activated and deactivated. In the activated state, the reservoir poppet is positioned so that the face is between the annular ring and the valve seat. When so positioned, the pump assembly functions as previously described with reference to the other embodiments. A compression of the pump bulb force the face against the valve seat and causes the cylinder poppet to open. A release of the pump bulb generates a vacuum which removes the reservoir poppet face from the valve seat and allows fluid to flow from the reservoir and into the pump bulb. Thus, the activated state is used when actively inflating the cylinders and while it is desired to maintain the cylinders in an inflated state.
In the deactivated state, the reservoir poppet is positioned so that the face moves through the annular ring. In this position, the face will be between the cylinder poppet and the annular ring and the reservoir poppet spring will bias the face so that it abuts the annular ring. In other words, the face is displaced from the valve seat, and a gap exists between the valve seat and the annular ring. The stem of the reservoir poppet extends from the face towards the cylinder poppet. The stem is a cylindrical member having a generally V-shaped groove extending about its circumference near the middle of the stem. The stem interacts with a flexible conical lip seal molded within the housing. When in the activated state, the conical lip seal is positioned near the V-shaped groove so that fluid flow is essentially unhindered. When in the deactivated state, the conical lip seal is caused to engage the cylindrical portion of the stem. Thus, a fluid tight seal can be formed.
When in the deactivated state, the reservoir poppet can be moved to engage and release the cylinder poppet, leading to a deflation of the cylinders. During this time, the conical lip seal continues to be located near the cylindrical portion of the stem; however, the flexible nature of the conical lip seal allows fluid flow in a direction from the cylinders to the reservoir. The pump assembly must be placed in the deactivated state to prevent spontaneous inflation. When in this state, the conical lip seal engages the cylindrical portion of the stem. If overpressure is generated, the reservoir poppet can be displaced towards the cylinder poppet. As this occurs, the increased fluid pressure levels force the conical lip seal to firmly abut the cylindrical portion of the stem, preventing increased pressure levels from reaching and displacing the cylinder poppet. Thus, spontaneous inflation is prevented.
To further improve the operational efficiency of the pump and valve assembly, in yet still another embodiment, a reservoir poppet is made of a metal material with a plastic member disposed over a segment of the metal material. The plastic segment of the reservoir poppet prevents undesired frictional contact (metal on metal) with other metal members, and prevents premature wearing of the contact point of the two components.
In another embodiment, a pump and valve assembly includes a pump bulb that is differentiated from the valve housing when inflation of the cylinders is desired. To supplement differentiation between the bulb and the valve housing, the valve housing is provided with a textured surface so that even through tissue the patient is able to readily discern which area comprises the pump bulb and which area comprises the valve housing. This is important in that the pump bulb is compressed for inflation while the valve housing is compressed for deflation.
The pump assembly is configured such that it has a length longer than its width, with its internal poppets running parallel with the length. To release fluid from the inflated cylinders, the internal poppets are actuated so that they move in a direction parallel to the length, until they open. To achieve this action directly, the opposing sides of the width of the valve housing are compressed. This compression causes actuation of the internal poppets.
In addition, an actuating bar is positioned within the valve housing parallel with and extending along at least one of the sides of the length. An arm attached to the actuating bar extends along a portion of one of the sides of the width in close proximity to the tip of one of the poppets. Thus, the configuration of the actuating bar causes it to engage and open the poppet allowing fluid to flow from the cylinder to the reservoir. Furthermore, the patient can grasp the valve housing in virtually any orientation and when pressure is applied, the actuating bar will act either directly or indirectly to open the appropriate poppets. Thus, so long as the patient grasps any portion of the pump and valve assembly other than the pump bulb, compression will result in the desired opening of the poppets which allows the cylinders to deflate.
Furthermore, since the patient can grasp the valve housing along the sides of the length, i.e., surfaces with larger surface area, less pressure need be applied to achieve the successful opening of the poppets. In other words, by increasing the surface area that is engaged by the patient""s fingers and appropriately positioning the actuating bar, less force need be exerted by the patient to achieve the desired result.
The textured surface of the valve housing not only helps the patient identify the correct portion of the pump and valve assembly to actuate, it also serves to prevent slippage once the patient begins to compress the housing. Thus, what is achieved is an efficient and ergonomic pump and valve assembly for an implantable prosthesis. The pump and valve assembly can advantageously be formed from a minimal number of components. That is, all that need be molded are a valve block and a corresponding pump bulb which surrounds the valve block. The various poppets can be inserted into the valve block and then placed within the interior of the pump bulb, thus forming a completed assembly. This results in certain manufacturing efficiencies, thus reducing both cost and time of production.
To prolong the life of the valve assembly, ribs are added to the actuating bar. The ribs increase the strength and stiffness of the actuating bar and prevent deflection during actuation. Permanent deformation of the actuating bar is prevented when normal deflection occurs during actuation. As a result, full axial motion of the poppet is ensured. Another rib is disposed along an actuation face of the actuating bar to also limit deformation during actuation.
To improve the ease of deflation, a stiff poppet support wraps around the valve body and rests against a portion of the check valve. The poppet support has a shelf that provides a smooth surface for a portion of the check valve to slide. The poppet support contacts the check valve and prevents undesirable sideways movement of the check valve against the valve body. The positioning and configuration of the poppet support thus allows the check valve to easily move axially into the valve body to an open position. This results in improved operational efficiency of the prosthesis pump and an extended operating life.
In most of the embodiments, the force generated by an overpressurization of the reservoir is used to prevent fluid flow into the cylinders.